Previous applications assigned to this assignee describe magnetically resonant transfer of power between antennas. The antennas may be capacitively loaded wire loops or multi-turn coils. These form a resonant antenna that efficiently couples energy from a primary structure (a transmitter) to a distal positioned secondary structure (a receiver) via a magnetic field. Both primary and secondary are tuned to a common resonance frequency.
These previous applications describe a major issue of wireless power as electromagnetic interference and radiation exposure for human safety. Energy transfer via magnetic field coupling may be mainly constrained by the specified H-field limits. Compliance with these limits may be tested at a defined distance, e.g., 10 m, from the radiating structure.